Select preferred group toggle/modal

[Amariithynar]

I don't want to block a group outright, but when reading a series often I have a preferred group to read, but another group might have a different upload format, so I have to constantly jump to the next correct chapter and then swap groups again because it uses alphabetical sorting only, currently.

I don't want a voting system or anything like that; just the option to have the site remember which group's work I actively chose. If someone doesn't, then the current format works fine. This would also integrate into the current "switch group" function pretty easily; just need to have a flag for which group was actively chosen using that option.